Slideshow: Poison Plants: Myths and Facts

Poison Plants Are Found Everywhere

Fact. Poison ivy, poison oak, and poison sumac grow in wooded or marshy areas throughout North America. The plants are not really poisonous, but they contain a sticky, long-lasting oil called urushiol that causes an itchy, blistering rash after it makes contact with skin. The slightest contact, even brushing up against the leaves, can leave urushiol on your clothing or skin. Poison ivy and poison oak grow as vines or shrubs. Poison sumac is a shrub or tree.

Poison Plants Have Three-Leaf Stems

Myth. Poison ivy is the only one of the three plants that always has three leaves, one on each side and one in the center. Its leaves are shiny with smooth or slightly notched edges. Poison oak looks similar, though larger and lobed like an oak leaf, with a textured, hairy surface. It can have groups of three, five, or seven leaves. Poison sumac leaves grow in clusters of seven to 13 leaves, with one leaf at the end.

Rashes Develop Right Away

Myth. The itchy rash forms within 24 to 72 hours of contact, depending on where it touches. It usually peaks within a week, but can last up to two to three weeks. A rash from poison ivy, oak, or sumac looks like patches or streaks of red, raised blisters. The rash usually does not spread unless urushiol is still making contact on the skin.

You Don't Have to Touch It to Get a Reaction

Fact. It’s usually safe to breathe where poison plants are growing. If you burn them in your yard, though, the smoke can be dangerous. Burning poison ivy leaves release chemicals that can irritate your eyes, nose, or lungs. You may need medical care if you breathe the smoke. Your doctor may prescribe steroids to control the symptoms.

Covering Up Helps Protect You

Fact. Keep your skin covered to avoid contact with these plants. Wear a long-sleeved shirt, long pants, gloves, and closed shoes if you're in an area where these plants are lurking. Tie the bottoms of your pants legs or tuck them into your boots. Gardeners should always wear gloves when handling bagged mulch or bales of pine straw. It's a good idea to keep a pair of shoes dedicated for outside use that can be kept outdoors. You can also use a lotion containing bentoquatam, which acts as a barrier between urushiol and your skin.

The Oil Can Stick to Your Skin

Fact. Urushiol begins to stick to your skin within minutes. If you know you have come into contact with poison ivy, oak, or sumac, immediately wash the area with lukewarm water and soap. If water is unavailable, rubbing alcohol or alcohol wipes can remove urushiol. Keep the affected area cool, dry, and clean. Wash your clothes and clean your boots or shoes. Hose down any garden tools.

Home Remedies Make the Rash Go Away

Myth. But home remedies and over-the-counter medicines can ease the itching and keep you more comfortable. Once a rash develops, keep it clean, dry, and cool. Using calamine lotion, diphenhydramine, or hydrocortisone can help control itching. Cool compresses or baths with baking soda or oatmeal can also help soothe the rash. Don't scratch. Scratching won't spread the rash, but can cause scarring or infection. Your doctor may also recommend other medications for your symptoms.

The Rash Is Contagious

Myth. If someone in your household has poison ivy, oak, or sumac, you can't "catch" it from them, even if you come into contact with the blisters. Just because you've never had a rash from one of these plants doesn't mean you're in the clear. Most people -- about 85% -- are allergic to urushiol. You can be affected by urushiol at any age.

You Won't Need to See a Doctor

Myth. See your doctor if the rash is close to your eyes or is widespread over your body. If needed, he can prescribe oral medications that will help with swelling and itching. Head to the emergency room if you have severe reactions in addition to the rash, such as nausea, fever, shortness of breath, extreme soreness at the rash site, or swollen lymph nodes. Call 911 if you are having any trouble breathing or feel faint.

Pets Don't Get the Rash

Fact. A dog or cat's fur usually protects its skin from urushiol. But urushiol can stay on a pet's fur and rub off on you. If your pet explores areas where poisonous plants are found, bathe him with soap and cool water. Be sure to wear gloves.

Use Any Method to Control Plants

Myth. Don't burn poison ivy, oak, or sumac. Particles of urushiol remain in the smoke and can aggravate the eyes, nose, and respiratory tract, and can land on the skin. Instead, dress appropriately and dig out the plants, getting as much of the root as possible. Put the plants in a plastic trash bag and dispose of them. Have someone else do this if you are very sensitive to the plant. Some herbicides may be effective. Read the labels carefully and apply at the right time of the year. Be careful -- urushiol remains active, even on dead plants.

THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.